lexical cast in C++11

cast.h

/* fallback */
template<class T>
T lexical_cast(const char* str)
{
    static std::istringstream ss; /* reusing has severe (positive) impact on performance */
    T value;
    ss.str(str);
    ss >> value;
    ss.clear();
    return value;
}

/* trivial conversion */
template<> std::string lexical_cast(const char* str) { return str; }

/* conversions that exist in stl */
template<> float lexical_cast(const char* str) { return std::strtof(str, nullptr); }
template<> long lexical_cast(const char* str) { return std::strtol(str, nullptr, 0); }
template<> long long lexical_cast(const char* str) { return std::strtoll(str, nullptr, 0); }
template<> unsigned long lexical_cast(const char* str) { return std::strtoul(str, nullptr, 0); }
template<> unsigned long long lexical_cast(const char* str) { return std::strtoull(str, nullptr, 0); }

/* conversions that need to be truncated */
template<> short lexical_cast(const char* str) { return static_cast<short>(lexical_cast<long>(str)); }
template<> int lexical_cast(const char* str) { return static_cast<int>(lexical_cast<long>(str)); }
template<> unsigned short lexical_cast(const char* str) { return static_cast<unsigned short>(lexical_cast<unsigned long>(str)); }
template<> unsigned int lexical_cast(const char* str) { return static_cast<unsigned int>(lexical_cast<unsigned long>(str)); }